Higher Doses of Vitamin E Needed

(Ivanhoe Newswire) -- Epidemiological data and previous animal studies suggested vitamin E, an antioxidant, could help protect patients at risk for suffering a heart attack. However, clinical studies have not been able to reproduce the effect in humans.

Now, scientists from Vanderbilt University Medical Center in Nashville, Tenn., report the previous studies on humans were not testing a high enough dose of vitamin E.

Antioxidants prevent oxidant injury, or oxidative stress, in the body by blocking the actions of highly reactive molecules called free radicals. These molecules have the ability to damage proteins and DNA. Free radicals are a normal byproduct of the body's metabolism, though bodies suffering from certain diseases, like heart disease, produce more of the destructive molecules.

"All of these studies were designed in a way that they never assessed the ability of the dose of vitamin E tested to effectively reduce oxidant stress," Jason Morrow, M.D., was quoted as saying.

In a new study, researchers determined at least 1600 international units per day are needed to cause a significant blockage of free radical damage. This dosage is twice as high as what researchers in some of the previous clinical trials used.

Study authors report, despite the massive dose, vitamin E did not have a major effect on oxidative stress. Also, because it is not known how safe taking such large doses would be in the long term, the study authors do not recommend people start taking this much vitamin E.

However, the study authors write future research on the effectiveness of antioxidants should strive to include an examination of effective doses.

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SOURCE: Free Radical Biology and Medicine, published online Aug. 22, 2007